Originally Posted by TVV
I do not see a tunkou/habaki on the wide bladed takouba. It is not unusual for takouba blades to be mounted with a sandwich construction to the hilt, especially older and re-used blades where the tang may have been compromised precluding being pinned. Per Iain's research, the wide bladed takoubas were status symbols, usually carried by Emir's bodyguards and all I personally see is extra decoration at the base of the blade, aimed at enhancing the prestige of the owner.
Totally agree, and that this hilt extension/sleeve on this wide bladed Tuareg sword appears to provide an elaborated panel for decoration.
As noted as well, Briggs (1965, pp.43 and 49, plates X and item T5) says,
"...occasionally blades were joined to the hilt by two plain or engraved plates of iron, sometimes almost as long as what remained of the blade proper.Although in some cases this seems to have been done to make possible use of a broken blade there are others in which there was no apparent use for it".
I believe the term for these sleeves or support plates to be 'adabel'.
While these seem to have some degree of functionality as a bolster, they are not directly related to the tunkou/habaki despite the obvious similarity.
Another instance of similar application are the bolster plates/hilt extensions in India on certain Hindu swords such as khanda and pattisa in the South.